js74

just got a 97 ex almost 2 months ago and realized that the gas milage isnt as good as what most people are saying that they are getting in there cars. on the highway im pushing it to get 23 mpg. the cars all stock and manual transmission. ive changed the plugs but thats been it, any ideas/suggestions?also when i first start driving it, it seems to bog down, if i push the clutch in, itll rev up fine, after its going for a little bit it doesnt seem to do it anymore.thanks in advance.

js74

anyone any ideas?

Jimster480

well it can def get better gas mileage than that. You might need a new air filter, PCV, fuel filter, spark plug wires, or motor (lol). You need to check all these things, and run some Techron through the car to clean out the fuel system.

How many miles are on the car?

Steven.

fuel filter/tune up

sloassSi

How many miles are on the car??? Change things above and that should help... make sure your engine is running up to par... is it smoking at all?

GotamaHuy

oil too. i got a hatch dx and i get 39 city/highway

js74

not sure of the miles, its not the original motor, it does need rings soon its burning alittle oil, im gonna fix this once the weather gets better, the whole motor is gonna be tore down and powder coated.

melitza03

I was having the same problem with bogging a bit going into first, and likewise, it would be ok once the clutch was pushed in. The problem seems to have been partially taken care of by replacing the cap & rotor (which were corroded all to hell). The mileage improved a tiny bit from that, and the bogging definitely declined - though it isn't gone.

Fuel filter is next on my list. Lemme know how it works out for you, too...

96hb

23mpg? That is terrible! I would do a complete tune up: plugs(make sure they are gapped properly), wires, distributor cap and rotor, fuel filter, air filter, PCV. Run some kind of injector cleaner in the gas. Change the oil and filter. Make sure your tires are at least pumped up to 32psi (I run mine a little higher for better mileage). Also you said this engine has been swapped out. Are you sure the correct ECU is being used? Do you have any CEL's?

jclark5093

wow my 97 auto got 34 highway...

fuel pressure regualtor anyone? Also, you might be running super rich, so check your injectors (I've had one stuck open before - you can use any old medical stethoscope to listen for the click click click while it's idling)

You didn't say you swapped the engine, did you? I'm not seeing that in the thread...

If you're stock, you're on a d16y8 vtec, right? My starting point would be the PCV and your pressures (oil, fuel, tires, air).

How is your driving style? even if you're super aggresive, you should get above 25 highway, though, methinks, in a 5spd, but what do I know? (lol)

just my 2 coppers.

96hb

He said it's not the original motor. Is it even a SOHC? What engine is it?

melitza03

Bumping this... when you say PCV, do you mean clean the valve, or just flat out replace it?

98civdx

^ just replace it, they are cheap. have you done a compresson test?

js74

i didnt do the swap, its the sohc non vtec, i cant remember the numbers on the motors, im a chevy guy, new to hondas but learning. ive only changed the plugs but havent, had the chance to do anything else with it because of the weather and girlfreind just having a baby.my driving isnt agressive, alittle over the speed limit but not real bad.

Jimster480

check what i said earlier.

Vindicator9000

Could be that your primary O2 is reading a bit weak. Maybe clogged cat, bad FPR, tire pressure, plugs/wires/distributor... there are lots of things that can cause it, and it's hard to diagnose without a trouble code.

Back when I had a d16y8 in my EX, I *averaged* about 36mpg, with a personal best of 40 (440 miles to the tank baby!). It seems like most people tend to get about 33-35 on that engine in that car. 23 is definitely indicative of a problem. I'm getting about 27-30 in mine now, and that's with a B18C1 and a B16 transmission.

Jimster480

wait what? 440 miles on a tank? 11 Gallons??? WTF I've never gotten my car past 10 gallons. Even when I had a stock motor, I stalled in the gas station and it took 10.01 Gallons :/

js74

kinda just going thru everything slow right now, i wanna pull the motor out soon an powder coat everything and replace everything that needs replaced(cap,rotor,plug wires).i plan on an aftermarked exhauste once i paint the car and put it back together so that will take care of the cat, hopefully once this is done itll run good again and get better gas milage.

Vindicator9000

It's all in how you drive it and maintain it. I don't usually get that good of mileage though; it's too boring. I managed it by doing a full tank of highway driving doing no more than 60mph, and always drafting behind semitrucks. I think 440 has to be just about the absolute limit on what a stock 00 EX can do.

96hb

The tank holds 11.9 gallons. Once I ran mine so low (just trying to see how far I could go) that when I filled up I was able to put in 12.3 gallons! I got 509 miles out of that tank. It was amazing!

Jimster480

wtf I can swear my tank is 10 gallons. My meter was below E the other day and it took 9.X and like I said the 1 time I took it until it was stalling out and I stalled in the gas station it only took 10.01 lol

jclark5093

it's 11.9 check the owners manual ;-)

and yeah, pcv are cheap, just replace it.

Sorry I didn't even think of the O2 sensors, that could definitely siphon some miles out of your tank...

If you're not throwing any CELs, though, my first place to start would still be pressures, and driving habits. Do you know if you're using the proper cpu for that engine? and how about engine/trans compatibility? if your power output far exceeds or doesn't meet the gear ratio requirement, you could be wasting power in the transfer.

Also, make sure your plugs and gaps are proper for your engine, so you *need* to know what engine you have. and if the head matches the block, and if it's been bored, cam swapped, etc. There should be a black metal bracket on the trans side of the motor indicating what model (or maybe it's engraved into the aluminum? not sure about all of them...)

Jimster480

oh I'm not saying that the manual doesnt say 11.9. I'm just saying that mine seems like its 10 and they failed to calculate it right when they made the car.
And yes the model of the engine is engraved into the aluminum on the front of the block.